Mold pollution is a key element of indoor air pollution that few people understand. Mold has been making the headlines more frequently over the last several years, largely as a result of Hurricane Katrina. And this year has brought wet weather to Canada and enormous record-breaking floods in the U.S. not seen in more than a century, including the massive overflow of the Mississippi River, certain to activate serious mold infestations in certain areas of the country.

If you live in one of those water-stricken areas, you could already be “sleeping with the enemy.”

Along with obvious places such as shower stalls and damp basements, there can be many hidden sources of mold in your home. Particularly, if you’ve had plumbing problems or leaks in your roof, mold may grow and release spores from places such as behind drywall, under carpet or carpet padding, or in wood.

But mold can find its way into some rather surprising places. One study found that even Christmas trees can breed mold, quietly releasing millions of spores into the room and causing winter allergies and asthma attacks. The study found that indoor air quality dropped six-fold over the 14 days a Christmas tree typically decorates a room. Millions of mold spores may even be hiding in your pillows.

And, maybe not surprisingly, if you live in a wet climate you may be even MORE at risk.